Stuttering is a complex and relatively frequent speech disorder, the causes of which are still unclear. In severe cases stuttering is a serious problem of communication, often causing secondary psychological problems. The general aim of this project is to increase our knowledge of the causal mechanisms of stuttering, and to develop and evaluate new methods of treatment. A new laboratory for neuropsychological and psychophysiological research on stuttering and related speech disturbances has been developed at the Department of Neuropsychology, Lund University. We are now able to analyse a variety of symptoms of speech disturbance and to experimentally investigate e.g. how stress and altered auditory feedback influence the severity of stuttering. In the first part of the project about 35 persons who stutter will be analysed regarding symptoms of stuttering and a variety of background factors and physiological and biochemical measures. A key goal is to discern different subtypes of stuttering, with possibly different causal mechanisms. In the next step research collaboration with the University of Alberta, Edmonton, Canada, is planned with the aim to further study causal mechanisms. We finally plan to use methods for functional brain imaging to study the cerebral organization of speech and hearing in people who stutter. We also plan to use such methods in combination with measures of symptoms to evaluate pharmacological effects.